Rheumatic heart disease remains endemic in the developing countries and is responsible for diseases associated with heart valves, and typically the mitral valve, affecting in general the younger population.
The functional consequences of these lesions are valvular stenosis, insufficiency or mixed lesions, and exploratory surgical treatment. Further, because of the severity of the lesions to the valve components, reconstructive valvular surgery may not be possible. In this case, substitution or valve replacement surgery by a mechanical valve or a bioprosthesis (composite of prosthetic and biological materials) may be required.
Mechanical prostheses have the advantage of better durability and the disadvantage of requiring life time anticoagulation and that in itself produces iatrogenic disease besides other complications such as hemorrhages, embolism and thromboembolism. An example of a mechanical prosthesis is shown in FIG. 1.
Bioprosthesis are made of a biological tissue mounted to a stent previously covered by a synthetic material in such a way as to provide a one way valve to reproduce to some extent the performance of a healthy human heart valve. An example of a bioprosthesis valve which operates without the subvalvular apparatus of the natural mitral valve is shown in FIG. 2. These bioprostheses have several advantages over the mechanical prostheses, such as, central flow, satisfactory hemodynamics, better quality of life, lower incidence of thromboembolism and bioprosthesis do not require the use of an anticoagulant.
The main drawback of the bioprosthesis is durability, especially in the younger population, due to the wear of the biological component, that is subject to high intraventricular pressures, and, in the case of the mitral valve; the current designs are not suitable to withstand high pressures and the specific flow pattern "VORTEX" of the left ventricle.
The natural mitral valve device includes a mitral annulus, mitral leaflets, subvalvular apparatus and the papillary muscles. The harmonic performance of this complex determines the adequacy of its intended function.